Apparatus for simultaneously precasting a plurality of structural members

ABSTRACT

Method and apparatus for precasting concrete wall panels having matched pairs of steel bearing plates cast therein. The wall panels are simultaneously precast in elongated casting beds in relative positions identical to the relative positions they are to occupy when employed in construction of a building. The wall panels are secured together in superposed relation in precise plumb and alignment by welding the matched pairs of bearing plates. The method and apparatus disclosed are suitable for precasting both slab wall panels and column-forming wall panels. A novel building structure is also disclosed which employs both slab wall panels and column-forming panels of the present invention in its construction.

[ 1 Dec. 18, 1973 APPARATUS FOR SIMULTANEOUSLY 1,998,448 4/1935 52/587 X 1,350,603 8/1920 Gerritson et 249/97 X 2,852,931 249/131 UX PRECASTING A PLURALITY OF STRUCTURAL MEMBERS Inventor:

9/1958 FOREIGN PATENTS OR APPLICATIONS Edward R. Sturm, Oklahoma City, Okla.

Primary Examiner-Robert D. Baldwin 1a k 0 s MC a r m mm mm V. mm mn. 0m ho TC e n .m s s A .1. 3 7

Attorney--Dunlap, Laney, Hessin and Dougherty [22] Filed: Sept. 30, 1970 [21] Appl. No.: 76,820

[57] ABSTRACT Method and apparatus for precasting concrete wall [52] :LS. 249/84, 249/85, 249/131 an l having matched pairs of steel bearing plates [51] nt.

wwz-m z uj cast therein. The wall panels are Simultaneously pre- 249/85, 84, 95,

[581 r'ieiaai'saai'cni.......i'.."IZZ'.'.......

cast in elongated casting beds in relative positions identical to the relative positions they are to occupy 25/118 H, 121 M; 52/587, 583, 584, 578; l 425/1 264/261 when employed in construction of a building. The wall panels are secured together in superposed relation in precise plumb and alignment by welding the matched pairs of bearing plates. The method and apparatus dis- S T N E A P UNITED STATES closed are suitable for precasting both slab wall panels and column-forming wall panels. A novel building structure is also disclosed which employs both slab 52/587 wall panels and column-forming panels of the present 5 2/5 X inventionin its construction. 1 52/587 X 25/121 M 15 Claims, 6 Drawing Figures M l 2 H 5 2 ..l. 249/84 X 25/121 M PATENIEUUEC 18 ms 3.779.505

v I M/VE/VTO? HUM/4P0 a sweM APPARATUS FOR SIMULTANEOUSLY PRECASTING A'iPLURALITY OF STRUCTURAL MEMBERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to improvements in building construction, and more particularly, but not by way of limitation to improvements in precast concrete form work and erection techniquesin building construction.

2. Description of thePrior Art The construction of multiple story building structures utilizing precast concrete structural members is well known. A common technique for constructing such buildings involves use of cast-in-place concrete and precast concrete structural members in varying ratios. Heretofore, however, the erection of precast structural members in precise plumb and alignment has been a difficult task, particularly in tall building structures. Also, the wind resistance of such structures has not been as great as desired. Construction costs in recent years have increased at a rapid rate necessitating that builders must seek more efficient and economical construction methods if newly constructed buildings are to compete with older buildings for the .rental' of floor space.

SUMMARY OF THE INVENTION The present invention relates to an apparatus for simultaneously precasting a plurality of structural members of cementitous-material. The structural members may be'easily'erected in superposed relation at a construction site in precise plumb and alignment. The app'aratus includes an elongated horizontal casting bed having a bottom side, a first side wall, a second side wall, a first end, and a second end. A first bearing plate is removably secured to the casting bed adjacent to said first end thereof. The bearing plate lies in a plane generally normal to the longitudinal center line of the casting bed, and is in continuous sealing engagement with the'first and second side walls and the bottom side of the casting bed."The bearing'plate forms a lateral wall across the casting bed thereby providing one end wall of a structural-member-forming cavity "in the casting bed. The bearing plate ultimately becomes'an integral part of the structural member to be cast in the cavity.

A second bearing plate is removably secured to the casting bed adjacent to the second end thereof. The second bearing plate lies in a plane generally normal to the longitudinal center line of the casting bed and is in continuous sealing .engagement with the first and second side walls and the bottom side of the casting bed. The second bearing plate fonns a lateral wall across the casting bed thereby providing another end wall of a -structural-member-forming cavity in the casting bed. The second bearing plate ultimately becomes an inteterline of the casting bed and is in continuous sealing engagement with the first and second side walls and the bottom side of the casting bed. The matched pair of bearing plates forms juxtaposed lateral walls across the casting bed thereby providing end walls for respective abutting structural-member-forming cavities. Each of the matched bearing plates ultimately becomes an integral part of the structural member to be cast in the respective cavity comprising the respective bearing plate.

Another aspect of the present invention relates to a second apparatus for simultaneously precasting a plurality of structural members of cementitious material, whereby the structural members may be easily erected in superposed relation at a construction site in precise plumb and alignment. The second apparatus includes a horizontal casting bed having a bottom side, a first longitudinal side wall, a second longitudinal side wall, a first end, and a second end. A first end wall extends laterally across and is removably secured to the lastmentioned casting bed adjacent to the first end thereof. The end wall lies in a plane generally normal to the longitudinal center line of the last-mentioned casting bed and comprises a plurality of removable headers and at least one bearing plate. Each bearing plate laterally separates the headers and ultimately becomes an integral part of the structural member to be cast adjacent thereto. A second end wall extends laterally across and is removably secured to the last-mentioned casting bed adjacent to the second end thereof. The second end wall lies in a plane generally normal to the longitudinal center line of the last-mentioned casting bed and comprises a plurality of removable headers and at least one bearing plate. The last-mentioned bearing plate laterally separates the last-mentioned headers and ultimately becomes an integral part of the structural member cast adjacent thereto. A transverse wall extends laterally across and is removably secured to the lastmentioned casting bed intermediate the first and sec ond end walls. The transverse wall lies in a plane generally normal to the longitudinal centerline of the casting bed and comprises a plurality of removable headers ber to be cast in the cavity comprising the respective bearing plate.

vA further-object of the invention is to provide apparatus for simultaneously precasting a plurality of concrete structural members which may be easily erected in precise plumb and alignment.

Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary perspective view showing the building structure partially erected.

FIG. 2 is a fragmentary perspective view of the apparatus for precasting exterior wall panels.

FIG. 3 is a fragmentary perspective view of the apparatus for precasting slab wall panels.

FIG. 4 is a plan view of the apparatus for precasting slab wall panels.

FIG. 5 is a fragmentary perspective view illustrating exterior wall panels erected in superposed relation.

FIG. 6 is a fragmentary perspective view illustrating slab wall panels erected in superposed relation as viewed from inside the central core structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention relates to a novel building structure comprised of precast concrete structural elements which are formed using novel methods and apparatus. Due to the multiple aspects of the present invention and in order to present a clear understanding thereof, the novel building structure of the present invention will be discussed first followed by discussion of novel methods and apparatus used to form certain precast concrete elements used therein.

Referring to the drawings and to FIG. 1 in particular the building structure constructed in accordance with the present invention is generally designated by reference character 10. A central core structure 12 is erected on a first foundation 14 of poured-implace concrete. The central core structure 12 includes a plurality of simultaneously precast concrete slab wall panels l6 whichare erected in vertical superposed relation from the first foundation 14 up through the full height of the building structure 10. I

The slab wall panels 16 are secured together in vertical relation by means of matched pairs of steel bearing plates 18 cast in the slab wall panels 16 as illustrated in FIG. 6. When the slab wall panels 16 are placed in proper position for. assembly, the matched pairs of bearing plates 18 are secured in proper position by means of bolts 20. Drift pins may be used in substitution for bolts. The bearing plates 18 are edge welded together and the plate extensions 22 may be burned off substantially flush with the slab wall panels 16. Wall attaching plates 24 are also cast in. the vertical edges of the slab wall panels. Wall attachlngplates 24 of horizontally adjacent slab wall panels 16 are welded together to secure said slab wall panels 16 together.

A second foundation 26 of poured-in-place concrete surrounds the first foundation 14. Four exterior walls 28 are erected on the second foundation 26. Each exterior wall 28 comprises a plurality of first vertical exterior wall columns 30 and a plurality'of second vertical exterior wall columns 32. Each first vertical wall column 30 comprises a plurality of first exterior wall panels 34 erected in superposed relation. Each second vertical wall column 32 comprises a plurality of second exterior wall panels 36 also erected in superposed relation. The exterior wall panels 34 and 36 are precast of concrete by a method which will be more fully described below.

A ledge 38 is formed on the inner surface of each first exterior wall panel 34 and on the inner surface of each second exterior wall panel 36. A supporting saddle 40 is formed on the inner surface of each second exterior wall panel 36. When the exterior wall panels 34 and 36 are erected, the ledges 38 formed thereon form a plurality of continuous horizontal floor slab supporting ledges 42 across each exterior wall 28.

A plurality of horizontally positioned elongated structural members 44 span between the second vertical wall columns 32 and the central core structure 12 at each floor level of the building structure. Each elongated structural member 44 is fixedly secured at its one end 46 in a respective pocket 48 of the centralcore structure 12 (see FIG.,6), and fixedly secured at its opposite end 50 to a supporting saddle 40 formed on a respective second exterior wall panel 36.

As illustrated in FIG. 1, the elongated structural members 44, located at any one floor level, are posi tioned parallel to one another. The longated structural members 44 located at all odd-numbered floor levels are horizontally aligned in one direction. The elongated structural members 44 located at all even-numbered floor levels are horizontally aligned at horizontal right angles to the direction of alignment of the elongated structural members 44 located at all odd-numbered floor levels.

Pre-stressed concrete first, second, and third double- T fioor slabs 52, 54 and 56, are located at each floor level of the building structure. The first double-T floor slabs 52 span between the central core structure 12 and the exterior walls 28. The second double-T floor slabs 54 span between the elongated structural members 44 and the exterior walls 28. The third double-T floor slabs 56 span between adjacent parallel elongated structural members 44.

The inner ends 58 of the first double-T floor slabs 52 are framed into respective pockets 60 formed in the slab wall panels 16 of the central core structure 12 and fixedly secured thereto. The outer ends 62 of the first double-T floor slabs 52 are supported by and fixedly secured to respective floor slab supporting ledges 42 formed on respective exterior walls 28.

The inner ends 64 of the second double-T floor slabs 54 are supported by and fixedly secured to respective elongated structural members 44. The outer ends 66 of APPARATUS FOR PRECASTING EXTERIOR WALL PANELS.

FIG. 2 illustrates an apparatus for simultaneously precasting exterior wall panels 34 and 36 and is generally designated by reference character 70. The apparatus 70 includes a support frame 72 and an elongated first casting bed 74 mounted horizontally thereon. The first casting bed 74 includes a first side wall 76, a second side wall 78 and a bottom side 80.

A first bearing plate 82 is removable secured to the first casting bed 74 adjacent the first end 84 thereof. The first bearing plate 82 lies in a plane generally normal to the longitudinal center line of the first casting bed 74. The first bearing plate 82 is in continuous sealing engagement with the first and second side walls 76 and 78 and the bottom side 80 of the first casting bed 74. The first bearing plate 82 forms a lateral wall across the first casting bed 74 thereby providing one end wall of a structural-member-forming cavity 86 in the first for fixedly securing the first bearing plate 82- to the exterior wall panel 34 or 36 to be cast in the adjacent structural-member-forming cavity 86.

A second bearing plate '90 is removably secured to the first casting bed 74 adjacent the second end 92 thereof. The second bearing plate 90 lies in a plane generally normal to the longitudinal center line of the first casting bed 74. The second bearing plate 90 is in continuous sealing engagement with the first and second side walls 76 and 78 and the bottom side 80 of the first casting bed 74. The second bearing plate 90 forms a lateral wall across the first casting bed 74 thereby providing one end wall of a structural-member-forming cavity 86 in the first casting bed 74.

Reinforcing bar studs 88 are fixedly secured to the second bearing plate 90. The reinforcing bar studs 88 extend perpendicularly outward from the second bearing plate 90 into the adjacent structural-memberforming cavity 86. The reinforcing bar studs 88 provide means for fixedly securing the second bearing plate 90 to the exterior wall panel 34 or 36 to be cast in the adjacent structural-member-forming cavity 86.

At least one matched pair of bearing plates 94 is removably secured to the first casting bed 74 intermediate the first and second bearing plates 82 and 90. The number of matched pairs of bearing plates 94 required is determined by the number of exterior wall panels to be simultaneously cast in the first casting bed 74.

Extensions 96 are formed-on each bearing plate 94. The bearing plates 94, comprising each matched pair, are secured together by means of shearable rivets 98.. Holes 100 are match-drilled in each riveted matched pair of bearing plates 94 through the extensions 96 formed thereon.

Each matched pair of bearing plates 94 lies in a plane generally normal to the longitudinal center line of the casting bed 74. Each matched pair of bearing plates 94 is in continuous sealing engagement with the first and second side walls 76 and 78 and the bottom side 80 of the first casting bed 74. Each matched pair of bearing plates 94 therefore forms a lateral wall across the first casting bed 74 thereby providing an end wall for each structural-member-forming cavity 86 adjacent thereto.

Reinforcing bar studs 88 are fixedly secured to each bearing plate 94 comprising the matched pair. The reinforcing bar studs 88 extend perpendicularly outward from each said respective bearing plate 94 into the respective adjacent structural-member-forming cavity 86. The reinforcing bar studs 88 provide means for fixedly securing the bearing plates 94 to the exterior wall panel 34 or 36 to be cast in the respective adjacent structural-member-forming cavities 86.

Reinforcing bars 102 are positioned in each structural-member-forming cavity 86. The reinforcing bars 102 are aligned substantially parallel to the longitudinal center line of the first casting bed 74. Each end 104 of each reinforcing bar 102 is secured in parallel relation to and supported by at least one reinforcing bar stud 88.

METHOD OF PRECASTING EXTERIOR WALL PANELS Any number of exterior panels 34 or 36 may be cast in the apparatus 70 at any one time, limited only by the predetermined length of each said panel and the length of the first casting bed 74. As an example, a 100 foot long casting bed is capable of simultaneously precasting," in one continuous pour of concrete all the exterior wall panels 34 required to erect an entire first vertical wall column eight stories high.

The same apparatus 70 may be prepared to cast either exterior wall panels 34 or 36. In the following discussion, exterior wall panels 34 will be used as an example, but it should be understood that the method is also applicable to wall panels 36.

After bearing plates 82, 90 and 94, reinforcing bar studs 88 and reinforcing bars 102 have been positioned in the first casting bed 74, as described above, concrete is poured into each structural-member-forming cavity 86 in the first casting bed 74. After sufficient time has been allowed for the concrete to cure, the exterior wall panels 34 are ready for removal from the first casting bed 74. It should be noted that after curing of the concrete, each bearing plate 82, 90 and 94 is fixedly secured to the respective exterior wall panel 34 adjacent thereto by means of the reinforcing bar studs 88 previ ously described. j

After marking each exterior wall panel 34 for later identification at the construction site, each said exte- 74 simultaneously, utilizing matched bearing plates 94,

the erection of the exterior wall panels 34 at the construction site is greatly simplified. The exterior wall panels 34 are erected in the same relative superposed positions in which they were cast, and therefore are in precise plumb and alignment after erection.

METHOD OF ERECTING EXTERIOR WALL PANELS A plurality of exterior wall panels 34 and 36 are erected on the second foundation 26 in vertical positions as illustrated in FIG. ll. Additional exterior wall panels 34 and 36 are erected on the respective firstmentioned exterior wall panels 34 and 36 in vertical superposed relation one on top of another. The number of exterior wall panels 34 and 36 to be vertically erected upwardly from the second foundation 26 depends on the height'of the building to be constructed. FIG. 5 illustrates exterior wall panels 34 in erected positions. When each exterior wall panel 34 is properly positioned on a respective lower exterior wall panel 34, bolts 20 are connected through holes in the extensions 96 of the bearing plates 94 to properly position and secure the exterior wall panels. Drift pins may be used instead of bolts 20 for this purpose. The bearing plates 94 of exterior wall panels 34 are edge welded together permanently securing the superposed exterior wall panels 34. The extensions 96 are then burned off of the bearing plates 94. It should be noted the above described erection technique is identical for erecting exterior wall panels 36.

APPARATUS FOR PRECASTING SLAB WALL PANELS FlGS. 3 and 4 illustrate an apparatus for simultaneously precasting slab wall panels 16 which is generally designated by reference character 106. The apparatus 106 includes a support frame 108 and a second casting bed 110 supported horizontally thereon. The

second casting bed 110 has a bottom side 112, a first longitudinal side wall 114, a second longitudinal side wall 116, a first end 118 and a second end 120.

A first end wall 122 extends laterally across and is removably secured to the second casting bed 11(1) adjacent the first end 118 thereof. The end wall 122 lies in a plane generally normal to the longitudinal center line of the casting bed. The first end wall 122 comprises four removable headers 124 and three bearing plates 126. The headers 124 are laterally separated by the bearing plates 126. The bearing plates 126 ultimately become integral parts of the slab wall panel 16 to be cast adjacent thereto.

A second end wall 128 extends laterally across and is removably secured to the second casting bed 110 adjacent the second end 120 thereof. The second end wall 128 lies in a plane generally normal to the longitudinal center line of the second casting bed 110 and comprises four removable headers 124 and three bearing plates 126. The bearing plates 126 laterally separate the headers 124. The bearing plates 126 ultimately become integral parts of the slab wall panel 16 cast adjacent thereto.

One or more transverse walls 130 extend laterally across and are removably secured to the second casting bed 110 intermediate the first end wall 122 and the second end wall 128. The transverse walls 130 lie in planes generally normal to the longitudinal center line of the second casting bed 110. Each transverse wall 130 comprises four removable headers 124 and three matched pairs of bearing plates 18. The removable headers 124 are laterally separated by the matched pairs of bearing plates 18. Each of the last mentioned bearing plates 18 ultimately becomes an integral part of the slab wall panel 16 to be-cast adjacent thereto.

Reinforcing bar studs 132 are fixedly secured to each of the bearing plates 18 and 126. The reinforcing bar studs 132 extend perpendicularly outward from the bearing plates 18 and 126 and are aligned generally with the center line of the second casting bed 110. The reinforcing bar studs 132 provide means for securing the bearing plates 18 and 126 to respective precast slab wall panels 16 to be cast adjacent thereto.

Pretensioned reinforcing strands 134 are supported both laterally and longitudinally within the second casting bed 110. Each reinforcing strand 134 will ultimately become an integral part of the respective slab wall panel 16 cast around the strand 134.

Holes 136 are formed in bearing plates 18 and 126. The matched pairs of bearing plates 18 are releasibly secured together by means of bolts 20 through holes 136 during the casting process. I

The first and second end walls 122 and 128 and the transverse walls 130 form structural-member-forming cavities 138 in the second casting bed 110.

METHOD OF PRECASTING SLAB WALL PANELS Any number of slab wall panels 16 may be cast in the apparatus 106 at any one time, limited only by the predetermined height of each slab wall panel 16 and the length of the second casting bed 110. As an example, a 100 foot long second casting bed 110 is capable of simultaneously casting, in one continuous pour of concrete, all the slab wall panels 16 required to erect a wall eight stories high.

After bearing plates 18 and 126, reinforcing bar studs 132, headers 124, and reinforcing strands 134 have been positioned in the second casting bed 110, as described above, concrete is poured into each structuralmember-forming cavity 138 in the second casting bed 1 10. After sufficient time has been allowed for the concrete to cure, the slab wall panels 16 are ready for removal from the second casting bed 110. It should be noted that after curing of the concrete, each bearing plate 18 and 126 is fixedly secured to the respective slab wall panel 16 adjacent thereto by means of the reinforcing bar studs 132 previously described.

Each slab wall panel 16 is marked for later identification at a construction site. The headers 124 are removed from the second casting bed exposing the pretensioned reinforcing strands 134 supported longitudinally therein. The longitudinal pretensioned reinforcing strands 134 are cut thereby prestressing the slab wall panels and permitting each completed slab wall panel 16 to be lifted from the second casting bed 110. Bolts 20 are removed from matched bearing plates 18. Each slab wall panel 16 is then lifted from the second casting bed 110.

METHOD OF ERECTING SLAB WALL PANELS A plurality of slab wall panels 16 are erected on the first foundation 14 in vertical positions as illustrated in FIG. 1. Additional slab wall panels 16 are erected on the respective first-mentioned slab wall panels 16 in vertical superposed relation one on top of another. The number of slab wall panels 16 to be vertically erected upwardly from the first foundation 14 depends on the height of the building to be constructed.

FIG. 6 illustrates slab wall panels 16 in erected positions. When slab wall panels 16 are erected, the adjacent matched bearing plates 18 are secured together by bolts 20. The bolts 20 are connected through holes 136 formed in extensions 22 of said bearing plates 18 to properly position the slab wall panels 16. Drift pins may be used for this purpose instead of bolts 20. Adjacent matched bearing plates 18 are edge welded together fixedly securing the superposed slab wall panels 16 in precise plumb and alignment. If desired, the extensions 22 may be burned off the matched pairs of bearing plates 18 substantially flush with the slab wall panels 16. The matched pairs of bearing plates 18 may then be completely edge welded to permanently secure the slab wall panels'16 in precise plumb and alignment. Horizontally adjacent slab wall panels 16 are secured together by welding together the respective adjacent bearing plates 24 cast therein.

From the foregoing it will be apparent that the present invention provides a novel building structure constructed of precast concrete structural elements. The present invention further provides novel apparatus for simultaneously precasting slab wall panels and exterior wall panels for use in construction of said building structure. Said novel apparatus provide precast slab wall panels and precast exterior wall panels which may be erected in precise plumb and alignment with a minimum amount of manual labor.

Changes may be made in the combination and arrangement of parts or elements as heretofore set forth in the specification and shown in the drawings without departing from the spirit and scope of the invention as defined in the following claims.

What is claimed is:

1. An apparatus for simultaneously precasting a plurality of structural members of cementitious material,

being in continuous sealing engagement with said first and second side walls and said bottom side of said casting bed, each additional intermediate wall comprising a matched pair of bearing plates formwhereby said structural members may be easily erected in superposed relation at a construction site in precise plumb and alignment, comprising:

an elongated horizontal casting bed having a bottom side, a first side wall, a second side wall, a first end, ing at least a portion of juxtaposed end walls for reand a second end; spective abutting structural-member-forming cavia first removable end wall removably secured to said ties in said casting bed, each of said additional casting bed adjacent to said first end thereof, said bearing plates to ultimately become an integral first end wall lying in a plane generally normal to part of the structural member to be cast in the rethe longitudinal center line of said casting bed and spective cavity comprising the respective bearing being in continuous sealing engagement with said plate and being removable from said casting bed first and second side walls and said bottom side of with the respective completed structural member; said casting bed, said first end wall comprising a and first bearing plate forming at least a portion of one means for fixedly securing each additional bearing end wall of a structural-member-forming cavity in plate to a respective structural member.

3. An apparatus for simultaneously precasting a plurality of structural members of cementitious materialas set forth in claim 1 characterized further to include:

said casting bed, said first bearing plate to'ultimately become an integral part of the structural member to be cast in said cavity and being removable from said casting bed with the completed structural-member-forming cavity in said casting bed, said second bearing plate to ultimately become an integral part of the structural member to be cast in said cavity and being removable from said casting bed with the completed structural member; and

' removable intermediate wall removably secured to said casting bed intermediate said first and second end walls, said intermediate wall lying in a plane at least one reinforcing bar stud fixedly secured to structural member; each of said bearing plates, said reinforcing bar second removable end wall removably secured to studs extending perpendicularly outward from said said casting bed adjacent to said second end bearing plates into the adjacent structuralthereof, said second end wall lying in a plane genermember-forming cavity, said reinforcing bar studs ally normal to the longitudinal center line of said being aligned substantially parallel to the longitudicasting bed and being in continuous sealing ennal center line of said casting bed and said reinforcgagement with said first and second side walls and ing bar studs providing said means for fixedly sesaid bottom side of said casting bed, said second curing each said bearing plate to the respective end wall comprising a second bearing plate forming structural member. at least a portion of another end wall of a 4. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 characterized further to include:

at least one reinforcing bar in each structuralmember-forming cavity, each said reinforcing bar to ultimately become an integral part of the structural member to be cast in said respective structural-member-forming cavity in which said reinforcing bar is supported.

5. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as 40 set forth in claim 4 wherein said reinforcing bars are supported in positions substantially parallel to the longitudinal center line of said casting bed. i

6. An apparatus for simultaneously precasting a plurality of structural members of cementitious material, whereby said structural members may be easily erected in superposed relation at a construction'site in precise plumb and alignment comprising:

generally normal to the longitudinal center line of said casting bed and being in continuous sealing engagem'ent with said first and second side walls and said bottomside of said casting bed, said intermediate wall comprising a matched pair of bearing plates forming at least a portion of juxtaposed end walls for respective abutting structural-memberforming cavities in said casting bed, each of said matched bearing plates to ultimately become an integral part of the structural member to be cast in the respective cavity comprising the respective a horizontal casting bed having a bottom side, a first longitudinal side wall, a second longitudinal side bearing plate and being removable from said castwall, a first end, and a second end; ing bed with the respective completed structural a first end wall extending laterally across and removmember; ably secured to said casting bed adjacent to said means for securing the matched bearing plates tofirst end thereof, said end wall lying in a plane gengether in a fixed position during the casting operaerally normal to the longitudinal center line of said tion, but permitting separation of the matched casting bed and comprising a plurality of removbearing plates upon removal of the structural memable headers and at least one bearing plate, each bers; and said bearing plate laterally separating said headers means for fixedly securing each of said bearing plates and ultimately becoming an integral part of the to a respective structural member. structural member to be cast adjacent thereto; 2. An apparatus for simultaneously precasting a plua second end wall extending laterally across and removably secured to said casting bed adjacent to said second end thereof, said second end wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at leastvone bearing plate, said last-mentioned bearing plate laterally separating said last-mentioned headers and ultirality of structural members of cementitious material as set forth in claim 1 characterized further to include:

at least one additional removable intermediate wall removably secured to said casting bed intermediate said first and second end walls, each additional intermediate wall lying in a plane generally normal to the longitudinal center line of said casting bed and mately becoming an integral part of the structural member cast adjacent thereto;

a transverse wall extending laterally across and removably secured to said casting bed intermediate said first and second end walls, said transverse wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at least one matched pair of bearing plates, said matched pair of bearing plates laterally separating said headers, each of said last-mentioned bearing plates to ultimately become an integral part of the structural member to be cast in the cavity comprising the respective bearing plate; and

means for fixedly securing each of said bearing plates to a respective structural member.

7. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 characterized further to include:

means for supporting a plurality of reinforcing strands within said casting bed, each said reinforcing strand to ultimately become an integral part of the respective structural member cast around said strand.

8. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 7 wherein said supporting means is adapted to support a portion of said reinforcing strands laterally across said casting bed in longitudinally spaced relation and the remaining reinforcing strands longitudinally lengthwise said casting bed in laterally spaced relation.

9. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 7 wherein said supporting means is adapted to support said reinforcing strands in a horizontal plane.

10. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 characterized further to include:

at least one additional transverse wall extending laterally across and removably secured to said casting bed intermediate said first and second end walls, each said additional transverse wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at least one matched pair of bearing plates, said matched pair of bearing plates laterally separating said headers, each of said lastmentioned bearing plates to ultimately become an integral part of the structural member to be cast adjacent thereto; and

means for fixedly securing each of said additional bearing plates to a respective structural member.

11. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 wherein the individual bearing plates of each said matched pair of bearing plates are releasably secured together in matched relation, each said matched pair of bearing plates to be separated after said cementitious material has cured.

12. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 11 wherein the individual bearing plates of each said matched pair of bearing plates are releasably secured together by means of shearable rivets, said rivets being adapted to shear simultaneously with the removal of each completed precast structural member from said casting bed.

13. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 wherein the individual bearing plates of each said matched pair of bearing plates are releasably secured together by means of shearable rivets, said rivets being adapted to shear simultaneously with the removal of each completed precast structural member from said casting bed.

14. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 characterized further to include:

at least one reinforcing bar stud fixedly secured to each of said bearing plates, each said reinforcing bar stud extending perpendicularly outward from the respective bearing plate to which it is fixedly secured and into the adjacent structural-memberforming cavity in said casting bed thereby providing said means for fixedly securing said bearing plates to respective precast structural members.

15. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 wherein said means for fixedly securing each of said bearing plates to a respective structural member is characterized further to include:

at least one reinforcing bar stud fixedly secured to each of said bearing plates, each said reinforcing bar stud extending perpendicularly outward from the respective bearing plate to which it is fixedly secured and into the adjacent structural-memberforming cavity in said casting bed. 

1. An apparatus for simultaneously precasting a plurality of structural members of cementitious material, whereby said structural members may be easily erected in superposed relation at a construction site in precise plumb and alignment, comprising: an elongated horizontal casting bed having a bottom side, a first side wall, a second side wall, a first end, and a second end; a first removable end wall removably secured to said casting bed adjacent to said first end thereof, said first end wall lying in a plane generally normal to the longitudinal center line of said casting bed and being in continuous sealing engagement with said first and second side walls and said bottom side of said casting bed, said first end wall comprising a first bearing plate forming at least a portion of one end wall of a structural-member-forming cavity in said casting bed, said first bearing plate to ultimately become an integral part of the structural member to be cast in said cavity and being removable from said casting bed with the completed structural member; a second removable end wall removably secured to said casting bed adjacent to said second end thereof, said second end wall lying in a plane generally normal to the longitudinal center line of said casting bed and being in continuous sealing engagement with said first and second side walls and said bottom side of said casting bed, said second end wall comprising a second bearing plate forming at least a portion of another end wall of a structural-member-forming cavity in said casting bed, said second bearing plate to ultimately become an integral part of the structural member to be cast in said cavity and being removable from said casting bed with the completed structural member; and a removable intermediate wall removably secured to said casting bed intermediate said first and second end walls, said intermediate wall lying in a plane generally normal to the longitudinal center line of said casting bed and being in continuous sealing engagement with said first and second side walls and said bottom side of said casting bed, said intermediate wall comprising a matched pair of bearing plates forming at least a portion of juxtaposed end walls for respective abutting structural-member-forming cavities in said casting bed, each of said matched bearing plates to ultimately become an integral part of the structural member to be cast in the respective cavity comprising the respective bearing plate and being removable from said casting bed with the respective completed structural member; means for securing the matched bearing plates together in a fixed position during the casting operation, but permitting separation of the matched bearing plates upon removal of the structural members; and means for fixedly securing each of said bearing plates to a respective structural member.
 2. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 characterized further to include: at least one additional removable intermediate wall removably secured to said casting bed intermediate said first and second end walls, each additional intermediate wall lying in a plane generally normal to the longitudinal center line of said casting bed and being in continuous sealing engagement with said first and second side walls and said bottom side of said casting bed, each additional intermediate wall comprising a matched pair of bearing plates forming at least a portion of juxtaposed end walls for respective abutting structural-member-forming cavities in said casting bed, each of said additional bearing plates to ultimately become an integral part of the structural member to be cast in the respective cavity comprising the reSpective bearing plate and being removable from said casting bed with the respective completed structural member; and means for fixedly securing each additional bearing plate to a respective structural member.
 3. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 characterized further to include: at least one reinforcing bar stud fixedly secured to each of said bearing plates, said reinforcing bar studs extending perpendicularly outward from said bearing plates into the adjacent structural-member-forming cavity, said reinforcing bar studs being aligned substantially parallel to the longitudinal center line of said casting bed and said reinforcing bar studs providing said means for fixedly securing each said bearing plate to the respective structural member.
 4. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 characterized further to include: at least one reinforcing bar in each structural-member-forming cavity, each said reinforcing bar to ultimately become an integral part of the structural member to be cast in said respective structural-member-forming cavity in which said reinforcing bar is supported.
 5. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 4 wherein said reinforcing bars are supported in positions substantially parallel to the longitudinal center line of said casting bed.
 6. An apparatus for simultaneously precasting a plurality of structural members of cementitious material, whereby said structural members may be easily erected in superposed relation at a construction site in precise plumb and alignment comprising: a horizontal casting bed having a bottom side, a first longitudinal side wall, a second longitudinal side wall, a first end, and a second end; a first end wall extending laterally across and removably secured to said casting bed adjacent to said first end thereof, said end wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at least one bearing plate, each said bearing plate laterally separating said headers and ultimately becoming an integral part of the structural member to be cast adjacent thereto; a second end wall extending laterally across and removably secured to said casting bed adjacent to said second end thereof, said second end wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at least one bearing plate, said last-mentioned bearing plate laterally separating said last-mentioned headers and ultimately becoming an integral part of the structural member cast adjacent thereto; a transverse wall extending laterally across and removably secured to said casting bed intermediate said first and second end walls, said transverse wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at least one matched pair of bearing plates, said matched pair of bearing plates laterally separating said headers, each of said last-mentioned bearing plates to ultimately become an integral part of the structural member to be cast in the cavity comprising the respective bearing plate; and means for fixedly securing each of said bearing plates to a respective structural member.
 7. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 characterized further to include: means for supporting a plurality of reinforcing strands within said casting bed, each said reinforcing strand to ultimately become an integral part of the respective structural member cast around said strand.
 8. An apparatus for simultaneously precasting a plurality of Structural members of cementitious material as set forth in claim 7 wherein said supporting means is adapted to support a portion of said reinforcing strands laterally across said casting bed in longitudinally spaced relation and the remaining reinforcing strands longitudinally lengthwise said casting bed in laterally spaced relation.
 9. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 7 wherein said supporting means is adapted to support said reinforcing strands in a horizontal plane.
 10. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 characterized further to include: at least one additional transverse wall extending laterally across and removably secured to said casting bed intermediate said first and second end walls, each said additional transverse wall lying in a plane generally normal to the longitudinal center line of said casting bed and comprising a plurality of removable headers and at least one matched pair of bearing plates, said matched pair of bearing plates laterally separating said headers, each of said last-mentioned bearing plates to ultimately become an integral part of the structural member to be cast adjacent thereto; and means for fixedly securing each of said additional bearing plates to a respective structural member.
 11. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 wherein the individual bearing plates of each said matched pair of bearing plates are releasably secured together in matched relation, each said matched pair of bearing plates to be separated after said cementitious material has cured.
 12. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 11 wherein the individual bearing plates of each said matched pair of bearing plates are releasably secured together by means of shearable rivets, said rivets being adapted to shear simultaneously with the removal of each completed precast structural member from said casting bed.
 13. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 wherein the individual bearing plates of each said matched pair of bearing plates are releasably secured together by means of shearable rivets, said rivets being adapted to shear simultaneously with the removal of each completed precast structural member from said casting bed.
 14. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 6 characterized further to include: at least one reinforcing bar stud fixedly secured to each of said bearing plates, each said reinforcing bar stud extending perpendicularly outward from the respective bearing plate to which it is fixedly secured and into the adjacent structural-member-forming cavity in said casting bed thereby providing said means for fixedly securing said bearing plates to respective precast structural members.
 15. An apparatus for simultaneously precasting a plurality of structural members of cementitious material as set forth in claim 1 wherein said means for fixedly securing each of said bearing plates to a respective structural member is characterized further to include: at least one reinforcing bar stud fixedly secured to each of said bearing plates, each said reinforcing bar stud extending perpendicularly outward from the respective bearing plate to which it is fixedly secured and into the adjacent structural-member-forming cavity in said casting bed. 